Locking device for interengaging screw-threaded elements



H. FAIRBANK LOCKING DEVICE FOR INTERENGAGING SCREW THREADED ELEMENTS.

APPLICATION FILED JAN. 31, 1921.

1,404,105, Patented Ian.17,1922..

Em; Fazirank ww UNITED STATES.

PATENT OFFICE.

HENRY FAIRBANK, OF LONDON, ENGLAND, ASSIGNOR OF ONE-HALF TO DOUGLASSTEWART MAULEVERER BROWN, OF WEST HAMPSTEAD, LONDON, N. W. 6,

ENGLAND.

LOCKING DEVICE FOR INTERENGAGING SCREXV-THREADED ELEMENTS.

Specification of Letters Patent.

Patented Jan. 17, 1922.

Application filed January 31, 1921. Serial No. 441,443.

To all whom it may concern:

Be it known that I, HENRY FAIRBANK, a subject of the King of England,residing at Wood Green, London, England, have in vented certain new anduseful Improvements in Looking Devices for lnterengaging Screw- ThreadedElements, of which the following is a specification. g

This invention relates to locking devices for securing two elements,which inter-engage by screwing one into the other, against accidentalmovement in the unscrewing clirection. The invention is particularlyapplicable to constructions wherein the one ele ment, for example a capscrew, that co -operates with another element, for example a base, has aface that approaches the other element when the first element is beingscrewed home on the second, and the invention has for its main object toprovide that the locking device shall be released automatically when theone element is screwed home on the other.

When the invention is applied to a greasebox having a cap for forcingthe grease out of the box, the cap is locked against unscrewing untilthe box has been emptied or nearly emptied by screwing the cap on to itas far as possible, whereupon the locking device is automaticallyreleased and the cap can be unscrewed for refilling the box.

The invention consists in the construction, arrangement and combinationof parts described hereinafter and pointed out in the claims.

One embodiment of the invention is illustrated in the accompanyingdrawing, where- Figure 1 is a bottom plan view of a greasebox with itslocking pawl in its engaging position, and V V Figure 2 is a verticalsection through the grease-box taken on the line 4-4 in Figure 1.

Like reference letters indicate like parts spond to, and form acontinuation of, one of the threads on the periphery of the base G. Whenthe cap is on the base, therefore, the nose will engage the bottom of athread of the cap. it will be seen that this nose is at such an anglethat it will lie approximately at a cutting angle to the surface of thecap it engages, and thus will tend to dig into the same if the cap isrotated in-the direction for unscrewing, but it will allow the cap to berotated in the direction for screwing on to the base, as it will thentrail around the inner face of the cap. To cause the nose to powerfullygrip the cap it is so pivoted that its nose lies only a little to oneside of a line passing through its point of pivoting, indicated at H andradial to the axis of rotation of the cap; the pawl thus acts virtuallyas a wedge between the cap and the base and will grip the cap even if itbe not provided with a sharp nose set at a cutting angle. To keep thepawl in operative position, a spring D is provided which spring bears atone end 'ainst a shoulder on the base, and at its Flier end against alug H on the pawl. The pawl is also provided with a horn H whichprojects over a hole in the base in which a pin J is movable endwise.This pin is also situated in the base that its direction of end wisemovement is parallel to the axis of pivoting of the pawl, its leadingend is conical and the point of the end is in line with one side of thehorn H It thus follows that if the pin J is advanced from the position 1shown in Figure 2, its conical end will force the horn H back and willthus release the operating nose H From the above description, it will beseen that the cap can be screwed on in the ordinary manner, but topermit it to be unscrewed, the pawl must be swung into an inoperativeposition in which it is released from the cap. For this purpose thenontapered end of the pin J projects towards that face of the cap whichis opposed to the base (Jr, and thus when the cap is screwed home thisface comes into contact with the pin and pushes it forward so that thepawl is brought into its inoperative position. The pin J is pushedsutliciently far down by screwing home the cap G to bring the parallelportion of the pin into contact with the horn l-l after the pawl hasbeen swung to the inoperative position, so that there is no tendency forthe pressure of the pawl to return the pin to its withdrawn position.The pin will thus remain in the advanced position and hold the pawlinope *ative, whilst the cap is unscrewed from the grease-box forrefilling or for any other purpose. To render the pawl operative again,it is only necessary to push the pin back from the under side of thegrease box. A circumferential rib J on the pin J limits its movement inboth directions.

What I claim as my invention and desire to secure by Letters Patent is:

1. The combination, with two co-axial screw-threaded elements, whereofone is screwed on the )eripher "of the other and has a face thatapproaches the other-when the said elements are being screwed home, of aspring-controlled pawl pivoted on one of said elements, to turn about anaxis parallel with the axis of said elements, which pawl has a nosearranged'normally to project beyond the element upon which it is mountedfor engaging the co-operating element, which nose is so formed that itis adapted to yield to movement of the one element relatively to theother in the screwing-on direction but tojam and hold the same in theunscrewing direction, and a releasing member which-is mounted on one ofsaid elements andis arranged to lie in the path of said face on theco-operating element and, when the one element is screwed home to beforced by contact with said face against the pawl in such direction asto move it into its disengaging position the said releasing member beingso constructed that it will remain in its in-operative position afterthe said face is withdrawn from the releasing member.

2. The combination. with two co-axial screw-threaded elements, whereofone is screwed on the periphery of the other and has a face thatapproaches the other when the said elements are being screwed home, of aspring-controlled pawl pivoted on one of said elements to turn about anaxis parallel with the axis of said elements, which pawl has a nose ar'anged normally to project beyond the element upon which it is mountedfor engaging the co-operating element, which nose is so formed that itis adapted to yield to movement of the one element relatively to theother in the screwing-on direction but to jam and hold the same in theunscrewing direction, and a releasing pin that is mounted on one of saidelements and is arranged to be moved endwise by said face in a directionparallel to the axis of pivoting of the pawl when the said elements arebeing screwed home,which pin has a cam-shaped end arranged to co actwith one side of said pawl, whereby the latter is driven into itsdisengaging position' when the pin is advanced.

3. The combination, with two co-aXial screwthreaded elements, whereofone a is screwed on the periphery of the'other and has a face thatapproaches the other when the said elements are being screwed home, of aspring-controlled pawl pivoted on one of said elements .to turn about anaxis parallel with the axis of said elements, which pawl has a nosearranged normally to project beyond the-element upon which it is mountedfor engaging the co-operating element, which nose is so formed that itis adapted to yield to movement of the one element relatively to theother in the screwing-on direction but to jam and hold the same in theunscrewing direction, a r leasing pin that is mounted'on one of saidelements and is arranged to be moved endwise by said face in a directionparallel to the {1X13 of pivoting of the pawl when the said elements arebeing screwedhome, which pin has a conical end arranged to co-act withone side of said pawl so that the latter is driven into its disengagingposition when tliepin is advanced, and means forlimiting the travel ofsaid pin in both directions a. In a lubricating device, the combinationwith an externally-threaded base-mem ber having a hole therein, of acap-screw screwed thereon, a' spring-controlled pawl pivoted on saidbase-member to turn about an axis parallel with the axisof rotation ofthe cap-screw, which pawl has a nose arranged to engagethe cap-screw,said nose being so formed that it is adapted to yield to movement of thecap-screw in the screwing-on direction,.but to jam and hold the same inthe unscrewing direction. and a releasing pin that is mounted on saidbasemember and is arranged to move endwise in a direction parallel withsaid axis, which pin has one end arranged to co-act with the closed endof said cap-screw when the latter is screwed home on said base-member,and has its other end cam-shaped and arranged to co-act with the side ofthe pawl and thrust the latter into its disengaged position when the pinis'advanced by the cap- 7 .screw.

In testimony whereof I afiix my signature.

HENRY FAIRBANK.

